Despite the advanced state of today's medical care, brain injury to newborn infants, e.g., after a difficult labor resulting in permanent neurological damage because the infant's brain did not receive sufficient oxygen-rich blood, occurs in an estimated 1 or 2 per 1000 births in the United States. Following the deprivation of the muchneeded oxygenated blood, neurons in the brain die over the course of minutes to days and are not capable of regeneration. In addition, glial cells which are essential for normal brain functioning can be lost.
There is scientific evidence that mild hypothermia of the affected infant's brain protects against neuronal damage in the case of hypoxic-ischemic insults to the brain. It has been reported that lowering the brain temperature to levels that are protective for neuronal damage facilitates improving the neurological and thus psycho-motor developmental outcome.
With this backdrop, several investigators have proposed particular devices for mild hypothermia of a newborn infant's brain. One such proposal is described and illustrated in the Dec. 16, 1997 edition of the Wall Street Journal and comprises a cooling cap wherein cooling water circulates through tubing that is coiled in a spiral configuration around the infant's head. The cooling water enters one end of the tubing adjacent the side of the infant's head and exits the tubing near the top of the infant's head.
Conventional tubing arranged in a spiral has a tendency to spring back and revert to its original shape. Therefore, external forces must be used to oppose the forces associated with the memory of the tubing over the entire surface of the infant's skull in order to maintain the tubing in contact with the head. While these forces may be effective to oppose the spring-back of the tubing, there is concern over the effect such forces have on the development on the newborn's fragile skull. Positioning the inlet for the cooling fluid near the side of the infant's head creates the risk that the infant may shift its head and thus pinch or otherwise impede flow into the tubing. Prior designs of cooling caps for an infant's head have not taken into account the change in temperature of the cooling fluid that occurs from the cooling fluid inlet to the cooling fluid outlet and the effect this has on cooling different portions of the brain. For example, in the cooling cap described above, the most extreme cooling occurs around the portion of the head just above the ears where the fluid enters the tubing and is the coldest, while less cooling would occur near the top of the head where the cooling fluid would be warmer.
Devices also exist for cooling the heads of adults, such as those undergoing chemotherapy treatment. It is reported that such treatment reduces the loss of hair as a result of the chemical treatment. An infant's skull is different in shape than an adult's skull, and is not fused and therefore very susceptible to external forces. The simple miniaturization of existing adult head cooling devices for use with infants is not appropriate due to the structural and shape differences between an adult skull and an infant skull.
In view of the foregoing, the need exists for an improved design for a device to cool an infant's brain so that effective utilization of the hypothermia treatment can be achieved.